---
id: "CVE-2009-1123"
kind: "vulnerability"
aliases: ["CVE-2009-1123"]
title: "Microsoft Windows: Microsoft Windows Improper Input Validation Vulnerability"
severity: "high"
cvss: 7.8
epss: 0.04878
exploited: true
status: "open"
category: "infrastructure"
products: [{"name": "Microsoft Windows", "fixed": [], "affected": "", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["exploited", "infrastructure", "self-hosted", "windows"]
not_affected_if: ["patched-windows"]
published_at: "2009-06-10T18:30:00+00:00"
first_seen_at: "2026-10-23T19:11:52+00:00"
updated_at: "2026-10-23T21:57:35+00:00"
sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2009-1123", "first_seen_at": "2026-10-23T19:11:52+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2009-1123", "first_seen_at": "2026-10-23T19:13:44+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2009-1123", "first_seen_at": "2026-10-23T21:57:35+00:00"}]
---

# Microsoft Windows: Microsoft Windows Improper Input Validation Vulnerability

The Windows kernel does not properly validate changes to certain kernel objects. A local user running a crafted application can gain higher privileges on the machine.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:Microsoft Windows affected ? fixed ?

## Fix

Apply the Microsoft updates for this CVE per vendor instructions, as CISA requires; the sources do not name the specific update or KB.

## Timeline

- 2026-10-23T19:11:52+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2009-1123
- 2026-10-23T19:13:44+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2009-1123
- 2026-10-23T21:57:35+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2009-1123

## From the sources

The kernel in Microsoft Windows 2000 SP4, XP SP2 and SP3, Server 2003 SP2, Vista Gold, SP1, and SP2, and Server 2008 SP2 does not properly validate changes to unspecified kernel objects, which allows local users to gain privileges via a crafted application, aka "Windows Kernel Desktop Vulnerability."

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_